Planting Terrariums and Wardian cases

Here’s how to set up a miniature landscape of house plants in a closed glass container. As well as being easy to make, this type of garden can look after itself for months on end.

Terrariums and Wardian cases are clear plastic or glass plant containers with sealed or close-fitting lids. They are as decorative as bottle gardens, but easier to set up, as you don’t have to squeeze plants through a tiny neck. Because the air inside them is moist, tropical plants, which dislike the dry air of central heating, thrive.

Terrariums and Wardian cases also protect plants from dust, smoke, gas fumes and sudden temperature changes, so they make ideal homes for a tiny fascinating jungle of greenery.

How terrariums and Wardian cases work

These containers recycle a plant’s own moisture, for months or even years. The water you first put in the potting mixture is taken up by the plant, then given off by the leaves into the surrounding air. The moisture can’t escape, so it condenses and runs down the container’s sides into the potting mixture, and the process begins again.

The plants and containers

Choose plants that are naturally small or slow growing. Flowering plants can be used, but may look dull once the flowers fade, and you have to dead head them, for appearance’s sake and to prevent disease. Most people use ‘green’ plants, though some are as colourful as flowers! The list on the back page has a good selection.

Some shops and garden centres sell house plant ‘tots’; tiny plants in 5cm (2in) pots, ideal for terrariums and Wardian cases. Choose a range of plant and leaf shapes, sizes and colours, as you would for a full-sized garden.

Real Wardian cases are costly, but inexpensive copies are made. Or use fish tanks, goldfish bowls, wide-mouthed glass storage jars, brandy snifters, salad and mixing bowls, old-fashioned glass battery tanks or glass-domed cake or cheese stands. Use a thick pane of glass as a lid, if the container has none of its own. For safety’s sake, bevel the edges.

Preparing and planting

Clean the container with lukewarm water, then dry it thoroughly. Place a 2.5cm (1 inch) layer of gravel in the bottom, with a few lumps of 15mm (1/2in) charcoal added. Cover with 5cm (2in) low-nutrient, or seed and cutting, potting mixture, to keep plants small.

Plant, then firm. Add a layer of gravel, if wished. Using a sprayer, water the plants, then replace the lid.

If the container will be seen from all sides, you can mound the potting mixture towards the centre. If viewed only from the front, mound the potting mixture towards the back. Add pretty stones or driftwood, if wished.

Place the plants, still in their pots, in the container, and move them around until you are happy with how they look. In front-facing containers, place the tallest plants towards the back; in ‘all-round’ ones, place them in the middle. Try not to have tall plants hiding low-growing ones.

You can bury the pots into the potting mixture of a large terrarium or Wardian case, otherwise, remove the plants from their pots first. Using a kitchen fork or spoon, make a hole in the potting mixture large enough to take the roots comfortably.

Where did the name Wardian case come from?

Nathaniel Ward, a Victorian doctor who discovered that delicate plants thrived in an enclosed glass case. Wardian cases were first used to ship exotic plants to England, and later became decorative features in the home.

I can’t see into my plastic terrarium because of water condensation. What should I do?

Condensation is worse on plastic than on glass, which sheds water more easily. Remove the lid, wipe the sides and replace the lid. If more condensation forms immediately, leave the lid off for a day or so. Cover with a 5cm (2in) layer of low-nutrient potting mixture.

Lay 2.5cm (1 inch) of gravel, with a few charcoal lumps mixed in along the bottom.